• Journal of Microbiology and Biotechnology
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• v.33 no.9
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• pp.1238-1249
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• 2023

In this study, we sought to investigate the production and optimization of biosurfactants by soil fungi isolated from petroleum oil-contaminated soil in Saudi Arabia. Forty-four fungal isolates were isolated from ten petroleum oil-contaminated soil samples. All isolates were identified using the internal transcribed spacer (ITS) region, and biosurfactant screening showed that thirty-nine of the isolates were positive. Aspergillus niger SA1 was the highest biosurfactant producer, demonstrating surface tension, drop collapsing, oil displacement, and an emulsification index (E₂₄) of 35.8 mN/m, 0.55 cm, 6.7 cm, and 70%, respectively. This isolate was therefore selected for biosurfactant optimization using the Fit Group model. The biosurfactant yield was increased 1.22 times higher than in the nonoptimized medium (8.02 g/l) under conditions of pH 6, temperature 35℃, waste frying oil (5.5 g), agitation rate of 200 rpm, and an incubation period of 7 days. Model significance and fitness analysis had an RMSE score of 0.852 and a p-value of 0.0016. The biosurfactant activities were surface tension (35.8 mN/m), drop collapsing (0.7 cm), oil displacement (4.5 cm), and E₂₄ (65.0%). The time course of biosurfactant production was a growth-associated phase. The main outputs of the mathematical model for biomass yield were Yx/s (1.18), and µ_max (0.0306) for biosurfactant yield was Y_p/s (1.87) and Y_p/x (2.51); for waste frying oil consumption the So was 55 g/l, and Ke was 2.56. To verify the model's accuracy, percentage errors between biomass and biosurfactant yields were determined by experimental work and calculated using model equations. The average error of biomass yield was 2.68%, and the average error percentage of biosurfactant yield was 3.39%.

• Korea Trade Review
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• v.48 no.4
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• pp.121-148
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• 2023

The rapid melting of Arctic sea ice has increased interest in the Northern Sea Route (NSR) as a viable alternative trade route between Europe and Asia. While extensive research has examined its competitiveness in terms of technical feasibility, safety, profitability, and environmental impact, the topic of the NSR ports remains relatively underrepresented in the literature. Hence, this study aims to contribute to the existing research by assessing the efficiency of 17 NSR ports to gain insights into their operations and identify areas for improvement using models of Data Envelopment Analysis(DEA). The obtained results show that efficient ports mainly belong to the western NSR region, with ports like Murmansk and Varandei consistently demonstrating high efficiency and constant returns to scale. Several ports, such as Onega, Arkhangelsk, Naryan-Mar, and Khatanga, showed inefficiencies in the utilization of berths and quay lengths. The findings not only contribute to academic knowledge but also offer practical implications for NSR port authorities, assisting them in making well-informed decisions regarding infrastructure development plans.

• Korean Journal of Ichthyology
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• v.35 no.4
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• pp.294-304
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• 2023

Seasonal variations in the community structure of larval fish assemblage in the coastal waters off Gadeok-do were investigated in May, August and November of 2019, and February in 2020. During the study period, a total of 85 larvae species belonging to 45 families were collected. The dominant species were Engraulis japonica, Gobiidae sp., Clupea pallasii, Decapterus maruadsi, and Callionymidae sp.. These five species accounted for 84.1% of the total number of larvae during the survey period. E. japonica, Gobiidae sp., D. maruadsi, and Callionymidae sp. were the dominant species in the summer, while C. pallasii was the dominant species in the winter. The Species Diversity Index was highest in the summer and lower in the fall and winter months, with the lowest values in the spring. As a result of cluster analysis using the number of individual larval fish showed that they are divided into four seasonal groups. In particular, due to seasonal changes in water temperature, an appropriate growth environment was formed in the summer, and an appropriate hatching water temperature for winter spawning fish species was formed in winter, reflecting the seasonal characteristics of the larval fish community.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.60 no.3
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• pp.228-234
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• 2024

To determine the diet of Ridged-eye flounder, Pleuronichthys cornutus in the South Sea of Korea, a total of 207 individuals were collected in 2022 (February, April, May, August, and November) and 2023 (January, February, April, July, and October) by the Fisheries science survey vessels of NIFS. The total length (TL) range of these specimens was from 14.1 to 33.9 cm, and the stomach contents of 100 individuals, not on an empty stomach, were analyzed. Polychaeta was the most important prey component in the diets of P. cornutus based on an Index of relative importance (%IRI) of 55.5%. Followed by amphipoda with a %IRI value of 21.3%. Polychaeta was an important component in diets across all size classes (< 20.0 cm, 20.0-25.0 cm, ≥ 25.0 cm) of P. cornutus; as they grew, the %IRI value of amphipoda decreased and the %IRI value of anthozoa and holothuroidea increased. There was also a significant increase in the mean weight of prey per stomach with growth. P. cornutus consumed polychaeta in all seasons, with spring and autumn being the most dominant seasons. In summer, gastropoda was the dominant prey, and in winter, holothuroidea was the dominant prey.

• Microbiology and Biotechnology Letters
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• v.52 no.1
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• pp.24-36
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• 2024

This study determines the combinatorial effect of enterocin MSW5 and five essential oils (EOs- Thymus vulgaris, Cymbopogon martini, Origanum vulgare, Cinnamomum zeylanicum, and Cymbopogon citrus) against Staphylococcus aureus, Listeria monocytogenes, and Salmonella Typhimurium. The Minimum Inhibitory Concentration of each antimicrobial agent was determined. The MIC of enterocin MSW5 against test pathogens was in the following order: S. aureus (0.362 ± 0.01), S. Typhimurium (0.362 ± 0.05 mg/ml), L. monocytogenes (0.725 ± 0.08 mg/ml). Among all EOs, maximum activity was observed in the case of C. zeylanicum against S. aureus (78.12 ± 0.04 ppm), S. Typhimurium (78.12 ± 0.08 ppm), and L. monocytogenes (39.00 ± 0.05 ppm). Further, the checkerboard assay was used to determine the synergistic effect between antimicrobial agents and enterocin MSW5 in combination with C. zeylanicum has shown significant synergism with the Fraction Inhibitory Concentration index (0.372) against test pathogens. Additionally, individual EOs and enterocin MSW5 have shown anti-biofilm activity, whereas their combined use has shown more significant antibiofilm activity. The maximum anti-biofilm activity was observed with the combination of enterocin MSW5 and O. vulgares against S. aureus (92.86 ± 0.06%) and S. Typhimurium (73.63 ± 0.23%) and a combination of enterocin MSW5 and C. citrus against L. monocytogenes (87.84 ± 0.15%). Therefore, combinations of antimicrobial compounds can control the growth of foodborne pathogens better than the individual agent.

• Fisheries and Aquatic Sciences
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• v.27 no.4
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• pp.231-239
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• 2024

Geray Reservoir is home to some fish species including Varicorhinus beso, Cyprinus carpio, Carasius carasius, Oreochromis niloticus, and Tilapia randelli. The V. beso is among the top fish-farming species for the reservoir. However, this data on total fish catch showed that the fish population is declining as a result of overexploitation of the stock. The purpose of this study was to set some management measures for the Geray reservoir using some biometric data on the most commonly caught fish-V. beso. A total of 170 fish samples (102 females and 68 males) ranging from 21 to 40.2 cm in total length (TL) and 94.6 to 618.4 g in total weight (TW) were gathered between October 2022 and May 2022 using a cast net with a mesh size of 6 cm. Nonetheless, it is thought that the sampling period is sufficient because the fish were spawning more during the month when the data was collected because of the high concentration of nutrients during that time. The overall male-to-female sex ratio in the population was 1:1.5, which differed considerably from the real ratio of 1:1 (x² = 6.8; p < 0.01). V. beso in the Geray reservoir exhibited virtually an isometric growth (b = 3) considering the length-weight relationships of males (TW = 0.0122TL^2.993) and females (TW = 0.0114TL^3.0139). The V. beso had an absolute fecundity (AF) of 2,190 to 11,265 eggs. AF was significantly correlated with TL, TW, and gonad weight (p < 0.01). V. beso's reproductive season peaked between November and May, with the gonadosomatic index ranging from 0.02 to 20.12 for females and 0.03 to 5.67 for males. The average V. beso condition factors for both sexes were higher than 1, indicating that the fish in the reservoir had properly developed, which may be the result of favorable habitat conditions.

• Journal of the Korean Society of Food Science and Nutrition
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• v.40 no.12
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• pp.1781-1786
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• 2011

This study was conducted to investigate the cause of microbiological contamination in yogurt and evaluate the effect of physicochemical treatment on the growth inhibition of Hanseniaspora uvarum isolated from yogurt. The yeast strain Hanseniaspora uvarum Y1 was subjected to heat and pH treatments. H. uvarum Y1 was killed at $70^{\circ}C$ and $80^{\circ}C$ after 15 min and survived in a wide pH range from pH 2 to 9. However, it did not survive under pH 1 and over pH 10. In a disk diffusion susceptibility test on H. uvarum Y1, a clear zone (5 mm) of growth inhibition was observed upon treatment with electrolyzed water. The effect of ozone gas on the growth of H. uvarum Y1 was evaluated by viable cell count. Initial cell numbers of $10^2$ and $10^3$ CFU/mL of H. uvarum Y1 were completely killed by treatment for 10 and 30 min, respectively. H. uvarum Y1 was also sterilized by microwave treatment for 1 min. When treated with gamma-irradiation, the rate of killing of H. uvarum Y1 was proportional to the irradiation dose. and complete killing occurred at a dose of 50 kGy.

• Journal of Life Science
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• v.22 no.2
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• pp.161-166
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• 2012

This study was performed to investigate the feeding effects of different additives on the growth performance and carcass characteristics of Holstein steers. Twenty-four Holstein steers, five months of age and 176.6 kg, were randomly allocated to three experimental groups of eight animals each for an 18-month feeding trial. The groups were control (not additive), T1 (fed zinc, vitamin C, and sulfur), and T2 (fed choline and lysine). The average daily gain was no different between the treatment groups during the growing to early fattening period, but it was significantly higher in the T1 group than the T2 group in the late fattening period (p<0.05). The final BW of the T1 group was relatively high in relation to the other groups, but was not significantly different. The additives had no effects on DMI during the experimental period; however, the feed conversion ratio of the T1 group in the late fattening period was significantly lower than that of the T2 group (p<0.05). The results of yield traits, carcass weight, and yield index were similar between groups, but back fat thickness and rib eye area were relatively lower in the T2 group than in the other groups. In terms of quality traits, meat color, texture, and maturity were not significantly different between the three groups. However, marbling score and appearance rate of high quality grade ($1^{++}$, $1^+$, and 1) were higher in the T1 group compared with the T2 group. Thus, the present results suggest that vitamin C, zinc, and sulfur supplementation may improve the growth performance and carcass characteristics of Holstein steers.

• Journal of Bio-Environment Control
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• v.20 no.2
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• pp.123-133
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• 2011

The objective of this study was to find optimal nutrient condition of container seedling production of two tropical species for high seedling quality. This study was conducted to investigate photosynthesis, chlorophyll fluorescence, chlorophyll contents, and growth performances of container seedlings of Eucalyptus pellita and Acacia mangium growing under four different fertilization treatments (Con., $0.5\;g{\cdot}l^{-1}$, $1.0\;g{\cdot}l^{-1}$, and $2.0\;g{\cdot}l^{-1}$ fertilization). E. pellita showed outstanding photosynthetic capacity, photochemical efficiency, and chlorophyll contents at $1.0\;g{\cdot}l^{-1}$ fertilization. Meanwhile, E. pellita showed the highest photosynthetic capacity, photochemical efficiency, and chlorophyll contents at $2.0\;g{\cdot}l^{-1}$ fertilization, as fertilization rate were increased, those of A. mangium increased. Like physiological characteristics, Both E. pellita at $1.0\;g{\cdot}l^{-1}$ fertilization and A. mangium at $2.0\;g{\cdot}l^{-1}$ fertilization were higher root collar diameter, height, biomass, and seedling quality index than other treatments. These results showed that E. pellita at $1\;g{\cdot}l^{-1}$ fertilization and A. mangium at $2.0\;g{\cdot}l^{-1}$ fertilization is optimal nutrient condition, respectively. Moreover, fertilization rate controlling is very important for growth and seedling quality of container seedling.

• Research in Plant Disease
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• v.21 no.4
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• pp.290-296
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• 2015

This study was conducted to establish an efficient screening system for resistant tomato to bacterial wilt caused by Ralstonia solanacearum. Under several conditions such as inoculation methods, growth stages of tomato seedlings, inoculum concentrations, and incubating temperatures after inoculation, development of bacterial wilt on nine resistant or susceptible cultivars of tomato was investigated. To inoculate by drenching the non-cut roots with the bacterial suspension was better to distinguish resistance and susceptibility of tomato cultivars than by drenching the cut roots using scalpel. And 'Hawaii7996' a resistant tomato to R. solanacearum showed high resistance at all the tested conditions including growth stages (3-, 6-, 8-, 10-leaf stages), inoculum concentrations ($OD_{600}=0.1-0.4$) and incubation temperatures (25, 30, $35^{\circ}C$). On the other hands, susceptible cultivars represented disease index of 3.7 and 3.9 at 6- and 8-leaf stages, respectively. At 3- and 10-leaf stages, the cultivars demonstrated lower disease severity of 2.1 and 0.5, respectively, than at 6- and 8-leaf stages. When the inoculated seedlings were incubated in growth chambers of 25, 30 and $35^{\circ}C$, disease severity of susceptible cultivars was significantly greater at 30 and $35^{\circ}C$ than at $25^{\circ}C$. In addition, the level of resistance of the tomato cultivars was not significantly affected by inoculum concentrations of $OD_{600}=0.1-0.4$. On the basis of the results, we suggest an efficient screening method to measure resistance level of tomato cultivars to bacterial wilt. The eight-leaf stage seedlings transplanted 7 days before inoculation, are inoculated with R. solanacearum by drenching the non-cut roots with a bacterial suspensions ($OD_{600}=0.4$) to give inoculum volume of 50 ml/soil l. The inoculated plants are incubated in a growth room at $30^{\circ}C$ for 12-13 days with 12-hour light a day.